"Huang, Ying" <ying.huang@xxxxxxxxx> writes:
> From: Huang Ying <ying.huang@xxxxxxxxx>
>
> In this patch, splitting huge page is delayed from almost the first
> step of swapping out to after allocating the swap space for the
> THP (Transparent Huge Page) and adding the THP into the swap cache.
> This will batch the corresponding operation, thus improve THP swap out
> throughput.
>
> This is the first step for the THP swap optimization. The plan is to
> delay splitting the THP step by step and avoid splitting the THP
> finally.
>
I found two issues in this patch, could you fold the following fix patch
into the original patch?
Best Regards,
Huang, Ying
------------------------------------------------------------->
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: [PATCH] mm, THP, swap: Fix two issues in THP optimize patch
When changing the logic for cluster allocation for THP in
get_swap_page(), I made a mistake so that a normal swap slot may be
allocated for a THP instead of return with failure. This is fixed in
the patch.
And I found two likely/unlikely annotation is wrong in
get_swap_pages(), because that is slow path, I just removed the
likely/unlikely annotation.
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
---
mm/swap_slots.c | 5 +++--
mm/swapfile.c | 4 ++--
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 78047d1efedd..90c1032a8ac3 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -309,8 +309,9 @@ swp_entry_t get_swap_page(struct page *page)
entry.val = 0;
- if (IS_ENABLED(CONFIG_THP_SWAP) && PageTransHuge(page)) {
- get_swap_pages(1, true, &entry);
+ if (PageTransHuge(page)) {
+ if (IS_ENABLED(CONFIG_THP_SWAP))
+ get_swap_pages(1, true, &entry);
return entry;
}
diff --git a/mm/swapfile.c b/mm/swapfile.c
index f4c0f2a92bf0..984f0dd94948 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -937,13 +937,13 @@ int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[])
spin_unlock(&si->lock);
goto nextsi;
}
- if (likely(cluster))
+ if (cluster)
n_ret = swap_alloc_cluster(si, swp_entries);
else
n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,
n_goal, swp_entries);
spin_unlock(&si->lock);
- if (n_ret || unlikely(cluster))
+ if (n_ret || cluster)
goto check_out;
pr_debug("scan_swap_map of si %d failed to find offset\n",
si->type);
--
2.11.0
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